opsu! is an unofficial open-source client for the rhythm game osu!, written in Java using Slick2D and LWJGL (wrappers around OpenGL and OpenAL).
opsu! runs on Windows, OS X, and Linux.
This is a fork of the original Android port of opsu!.
Before building, make sure that all of the git submodules are up to date:
git submodule update
Then build with the standard Android Studio Gradle tasks:
./gradlew assembleDebug
Output will be in android/build/outputs/apk/
This software is licensed under GNU GPL version 3. You can find the full text of the license here.